This is a quick guide for if you want to save only the audio from a file. This is very simple, but quite useful.

1. Load the video file.
2. Optional: Set the A & B positions if you want only a portion of the audio track.
3. From the side panel, Audio section, choose the audio codec you want to use(nbsp)(ndash) e.g. MP3, Vorbis, WAV, AAC, or Copy if you just want to extract a piece of the original soundtrack.
4. Configure the options for your audio codec using the Configure button.
5. Go the menu: Audio → Save.
6. Save the audio file.

A note of warning: using that method will save the raw audio track. If it is AAC or Vorbis, you will end up with an unplayable file as they need a container to be playable. (Git head can export AAC in ADTS container)